Green electricity has been around a while and for those who really care about the environment – it’s an obvious energy choice. But now consumers can also sign up to green gas. So what is green gas and how eco-friendly is it really? We chat to Douglas Stewart of Green Energy UK…
What is green gas?
Green gas (or Biomethane as it is sometimes called) is gas derived from the processing of organic waste.
Fossil fuel gas is derived from the liberation of carbon that has been captured over millions of years; a sort of pent up supply being released at a different rate to that at which it was produced
Biogas in contrast is merely releasing carbon from organic matter that has recently been produced. So it corresponds to what we understand as recycling.
It’s also important to note that by processing it in this way we prevent Methane a ‘greenhouse gas’ 20 times more potent than CO2 from leaking the atmosphere.
Where does it come from?
Green gas is derived from processing Organic material, examples of which are waste food, waste crops, animal waste, fish waste, food processing waste, anything organic which will decompose or rot if left to its own devices.
So it’s taking things that have no useful purpose to society, which in the past would probably have gone to landfill and put it to good use, ‘where there’s muck there’s power’ to paraphrase an old saying.
What’s the technology behind creating green gas?
Generally it is anaerobic digestion (AD) but it can also be obtained via processes called gasification or pyrolysis. These are more nascent technologies and require superheating.
Anaerobic digestion is the natural breakdown of organic materials into methane and Carbon Dioxide. Typically an anaerobic digester is a sealed vessel in which bacteria act without oxygen; you might have seen big round silos with bulbous covers at a farm. The organic material needs to be fully mixed and warmed, usually to body temperature. This process produces Biogas which is 70% methane and 30% carbon dioxide which can be used to create electricity through Combined Heat and Power engines. The residue or digestate is often used as fertiliser.
However removing the CO2 and other trace gases, a process called scrubbing or upgrading, produces a renewable gas called Biomethane which can be introduced into the gas grid for consumption in our homes and businesses.
Why is it a good idea?
Environmentally, the material used in the process would decompose naturally and through that Methane would be given off into the atmosphere; it’s a gas 20 times more toxic that CO2
But in terms of energy security the UK is now a net importer of Gas and therefore generating our own Biogas means we become less reliant on volatile areas of the world for our fuel.
How eco-friendly is green gas?
Well I think you can see from the above that it makes good use of waste, recycling it and creating energy and reducing methane leakage. It deals with an unpleasant side of our 21st century lifestyles in an eco-friendly way and as it becomes more popular it will replace an increasing percentage of what’s called natural gas, but is a fossil fuel, in the system. The key difference between the two gases is that natural gas is created over millions of years and biogas is produced in days.
Where is the UK currently when it comes to generation and consumption of green gas in comparison to other types of less environmentally sensitive gases?
It’s early days for the green gas industry. While AD gas has been produced for a number of years it is only recently that the scrubbed or upgraded gas has been permitted to be introduced into the National Grid. Up until then it was just natural gas that was supplied to our homes and businesses with its attendant climate change concerns.
What does the future look like for green gas in the UK?
It looks like a growth industry.
While we continue to produce waste, we need somewhere to put it and land fill is fast running out, so we have to find other options. Collecting and processing waste isn’t new – what’s new is the ability to create biomethane that can be injected into the Gas Grid to power homes and businesses in a ‘recycling’ and environmentally friendly way.
Name of interviewee: Doug Stewart
Company name: Green Energy UK PLC